Defroster control or the like



Jan. 17, 1967 s. E. SORENSEN ET AL 3,299,237

DEFROSTER CONTROL OR THE LIKE Filed March 2, 1964 3 Sheets-Sheet 2 FIG.3

INVENTORS SVEND E. SORENSEN WILLIAM L. MCHALE BY $064M THEIR ATTORNEYS Jan. 17, 1967 s. E. SORENSEN ET AL 3,299,237

DEFROSTER CONTROL OR .THE LIKE Filed March 2, 1964 3 Sheets-Sheet 3 FIG.5

INVENTORS SVEND E. SORENSEN $1 I J WILLIAM L. McHALE I I 1 1 l I III BY =5; 2 a a F i 6.6 mm ATTORNEYS United States Patent ware Filed Mar. 2, 1964, Sel. No. 348,458 Claims. or. 200-140 This invention relates to an improved defroster control device for defrosting an evaporator coil in a heat pump, refrigeration system, or the like.

In addition, this invention relates to improved parts for --such a defroster control device or the like.

It is well known that in refrigeration systems, such as a heat pump system, there is provided an outside heat exchanger which is exposed to the atmosphere and an inside heat exchanger which is exposed to the air in the building or dwelling.

During the cooling cycle of such a heat pump system, the compressor delivers the refrigerant to the outside heat exchanger whereby the same acts as a condenser and gives up the heat of the refrigerant to the outside air While the inside heat exchanger functions as an evaporator and absorbs heat from the air passed thereover whereby the interior of the building or dwelling is cooled.

By actuating a suitable reversing valve in the heat pump system, the refrigerating cycle can be reversed whereby the inside heat exchanger acts as a condenser and gives up heat to the air of the building or dwelling while the outside heat exchanger acts as the evaporator and absorbs heat from the outside air.

However, it is also well known that during the heating cycle of such a heat pump system, ice and frost is adapted to form on the surfaces of the outside heat exchanger when the same functions as an evaporator whereby the ice formation substantially reduces the rate of heat exchange to adversely affect the efficiency of the system when the same is being utilized on the heating cycle thereof.

Therefore, some means must be provided to automatically defrost or de-ice the outside heat exchanger when the same is acting as an evaporator during the heating cycle of the system.

According to the teachings of this invention such a control device is provided which will initiate the defrosting of the evaporator when the pressure drop across the coil thereof reaches a predetermined value and which will automatically terminate the defrosting when the temperature of the coil has reached a predetermined value.

The control device of this invention is adjustable over a wide pressure and temperature range, has the feature of being self locking so no false defrosting can take place during cooling operations thereof and the same is so balanced that it is insensitive to vibrations in any of its mounted positions.

Accordingly, it is an object of this invention to provide an improved defroster control device or the like having one or more of the novel features set forth above or here inafter shown or described.

Another object of this invention is to provide improved parts for such a defroster control device or the like.

Other objects, uses and advantages of this invention are apparent from a reading of this description which proceeds with reference to the accompanying drawings forming a part thereof and wherein:

FIGURE 1 is :a schematic view illustrating one typical application of the control device of this invention.

FIGURE 2 is a perspective view of the control device of this invention.

FIGURE 3 is an enlarged cross-sectional view taken on line 33 of FIGURE 2.

FIGURE 4 is a reduced cross-sectional view taken on line 44 of FIGURE 3.

FIGURE 5 is a view similar to FIGURE 3 and illustrates the control device in another operating position thereof.

FIGURE 6 is an end view of the control device illustrated in FIGURE 2.

While the various features of this invention are hereinafter described and illustrated as being particularly adaptable to provide a defrosting control device, it is to be understood that the various features of this invention can be utilized singly or in any combination thereof to provide other devices as desired.

Therefore, this invention is not to be limited to only the embodiment illustrated in the drawings, because the drawings are merely utilized to illustrate one of the wide variety of uses of this invention.

Referring now to FIGURE 1, a typical heat pump system is generally indicated by the reference numeral 10 and includes an outside heat exchanger 11 and an inside heat exchanger 12. A refrigerant compressor 13 has the outlet side thereof interconnected to a reversing valve 14 by conduit 15 while the inlet side of the compressor 13 is interconnected to the reversing valve 14 by a conduit means 16.

One side of the outside heat exchanger 11 is interconnected to the reversing valve 14 by a conduit means 17 while the other side of the heat exchanger 11 is interconnected to one side of the heat exchanger 12 by a conduit means 18 having a capillary restriction 19 therein in a conventional manner. The other side of the inside heat exchanger 12 is interconnected to the reversing valve 14 by a conduit means 20.

When it is desired to utilize the system 10 for a cooling cycle, a selector switch 21 is disposed in an appropriate position thereof to cause the outlet side 15 of the compressor 13 to be interconnected to the conduit 17 of the outside heat exchanger 11 through the reversing valve 14 so that the outside heat exchanger 11 acts as a condenser and gives up its heat to the outside air whereby the inside heat exchanger 12 will act as an evaporator to cool the air circulated around the same, the outlet side 20 of the inside heat exchanger 12 being interconnected to the inlet side 16 of the compressor 13 by the reversing valve 14.

When it is desired to utilize the system 10 for a heating cycle thereof, the selector valve 21 is disposed in the appropriate position thereof so that the reversing valve 14 will reverse the flow of refrigerant through the system.

In particular, the reversing valve 14 now interconnects the outlet 15 of the compressor 13 with the conduit means 20 of the inside heat exchanger 12 whereby the same acts as a condenser and gives up the heat to the inside air circulated around the same. In this manner, the outside heat exchanger 11 now acts as an evaporator with the conduit means 17 thereof being interconnected to the inlet side 16 of the compressor 13.

Usually the outside heat exchanger 11 is disposed in a duct work 22 so that air can be circulated from the right to the left through the heat exchanger 11 by a suitable fan 23 driven by an electrical motor 24 or the like.

However, when the outside heat exchanger 11 is acting as an evaporator, frost and ice is adapted to form on the same to impede the flow of air therethrough whereby the efficiency of the system 10 is substantially decreased.

According to the teachings of this invention, an improved defroster control device 25 of this invention is provided and is adapted to automatically initiate a defrosting of the outside heat exchanger 11 when the pressure drop across the heat exchanger 11 reaches a predetermined value in the manner hereinafter described to cause the reversing valve 14 to again reverse the flow of refrigerant therethrough so that the heat exchanger 11 will temporarily act as a condenser and, thereby, heat up to melt the ice and frost thereon. Such defrosting operation is automatically terminated by the control device 25 of this invention when the temperature of the heat exchanger 11 has reached a predetermined value whereby the control device 25 then permits the reversing valve 14 to reverse the flow of refrigerant through the system to cause the heat exchanger 11 to again act as an evaporator for the heating cycle of the system 10.

The particular details of the control device of this invention will now be described and reference is made to FIGURES 2-6.

As illustrated in FIGURES 2 and 3, the control device 25 of this invention includes a first housing 26 defined by a pair of cup-shaped metal members 27, 28 respectively secured together at the outer peripheries thereof by having a flange 29 of the member 28 bent over a flange 30 of the member 27 to trap a sealing gasket 31 there-between to completely sea l close the housing members 27 and 28 and define a compartment 32 therebetween.

A movable diaphragm means 33 is also disposed in the first housing 26 and divides the compartment 32 thereof into two chambers 34 and 35, the chamber 34 adapted to be interconnected to the inlet side of the outside heat exchanger 11 by a conduit means 36, FIGURE 1, being interconnected to an inlet nipple 37 carried by the housing member 27 while the chamber is adapted to be interconnected to the outlet side of the outside heat exchanger 11 by a conduit 38 being interconnected to an inlet nipple 39 carried by the housing member 28.

In this manner, the pressure differential between the inlet side and outlet side of the duct work 12 of the system 10 is sensed by the diaphragm means 33 whereby the diaphragm means 33 is adapted to move from the position illustrated in FIGURE 3 to the position illustrated in FIGURE 5 when the pressure differential exceeds a predetermined limit in a manner herein-after set forth to cause the control device 25 to automatically defrost the heat exchanger 11 in the manner previously described, such leftward movement of the diaphragm means 33 from the position illustrated in FIGURE 3 to the position illustrated in FIGURE 5 being limited by suitable stop means 40 carried by the diaphragm means 33 and engageable with the inside surface of the housing member 28.

A second housing 41 is provided and is formed from a plurality of members 42, 43 and 44 suitably interconnected together to define a compartment 45 in the housing 41, the housing 41 being suitably secured to the housing 26 by rivets 46 or the like.

The housings 26 and 41 respectively have aligned openings 47 and 48 provided therein to receive a shaft-like member 49 having one end 50 thereof interconnected to the diaphragm means 33 in any suitable manner whereby the other end 51 of the shaft-like member 49 projects into the compartment 45 of the housing 41 and moves axially therein upon movement of the diaphragm means 33.

An annular sealing member 52 is disposed between the housings 26 and 41 and surrounds the openings 47 and 48 thereof, the sealing member 52 carrying a flexible disclike sealing member 53 having its outer periphery 54 attached to the sealing member 52 and its inner periphery 55 secured to an annular sealing member 56 disposed in an annular recess 57 of the shaft-like member 49.

In this manner, the chamber 35 of the housing 26 is fully fluid sealed from the exterior of the housing 26.

A first lever 58 is disposed in the compartment 35 of the housing 41 and is pivotally mounted at a fulcrum point 59 intermediate the opposed ends 60 and 61 of the lever 58. The end 61 of the lever 58 has a circular recess 62 receiving the end 51 of the shaft-like member 49 whereby leftward movement of the shaft-like member 49 from the position illustrated in FIGURE 3 to the posi- 4 tion illustrated in FIGURE 5 causes the end 60 of the lever 58 to move in a clockwise direction.

The end 60 of the lever 58 engages the plunger 63 of an electrical switch construction 64 comprising a housing 65 secured in the compartment 45 of the housing 41 in any suitable manner and carrying a pair of fixed electrical contacts 66 and 67 and a movable contact 68 movable between the contacts 66 and 67 for a purpose hereinafter described.

The movable contact 68 is carried on one end of a spring blade 69 having the other end 70 thereof fastened to the housing 65 and an actuating member 71 is pivotally mounted in the housing 65 at a point 72 and is engage able by the plunger 63, the actuating member 71 being interconnected to one end 73 of a rolling spring 74 having the other end 75 thereof interconnected toa movable toggle member 76 pivotally mounted to the spring blade 69 at points 77. The toggle member 76 has an outwardly extending leg 78 movable between fixed shoulders 79 and 88 of the housing 65.

'When the plunger 63 is disposed in its inward position illustrated in FIGURE 3, the rolling spring 74 maintains the contact 68 into electrical contact with the contact 67 whereby the contacts 66 and 68 are opened.

However, when the plunger 63 is adapted to move to the right from the position illustrated in FIGURE 3 to the position illustrated in FIGURE 5 by the force of the spring blade 69, the rolling spring 74 is adapted to snap the contact 68 out of electrical contact with the contact 67 and into electrical contact with the contact 66 whereby the contacts 68 and 66 are closed in themanner illustrated in FIGURE 5.

The electrical contacts 68 and 66 of the electrical switch construction 64 are so interconnected to the reversing valve 14 that when the reversing valve 14 is causing the system 10 to operate on its heating cycle and the contacts 68 and 66 are closed in a manner hereinafterdescribed, the reversing valve 14 is actuated by a suitable solenoid or the like in a manner to cause a reversing of the refrigerant in the system 18 to temporarily cause the heatexchanger 11 to act as the condenser and defrost the same whereby when the contacts 66 and 68 are again opened to the position illustrated in FIGURE 3, the reversing valve 14 will operate the system 10 on its heating cycle so that the heat exchanger 11 acts as an evaporator.

A compression spring 81 is disposed in the compartment 45 of the housing 41 and has one end 82 thereof received in a recess 83 formed in the end 61 of the lever 58 on the side thereof opposed to the shaft-like member 49, the other end 84 of the compression spring 81 being interconnected to a threaded adjusting member 85 threadedly disposed in a threaded bore 86 passing throughthe housing member 44.

In this manner, the force of the compression spring 81 tending to move the shaft-like member 49 to the right can be varied by adjusting the member 85 relative to the housing 41, the adjusting member 85 having an enlarged bifurcated head 87 disposed exteriorly of the housing 31 so that the same can be readily adjusted even after the control device 25 has been mounted in the system 10 in the manner illustrated in FIGURE 10.

Thus, it can be seen that the desired pressure differential between the chambers 34 and 35 of the housing 26 can be selected by the spring 81 which will cause the lever 58 to pivot from the position illustrated in FIGURE 3 to the position illustrated in FIGURE 5 and cause the switch means 64 to defrost the evaporator 11 in the manner previously described.

A second lever 88 is pivotally mounted to the housing 41 in the compartment 45 at a fulcrum point 89 whereby the end 96 of the lever 88 is adapted to engage the end 61 of the lever 58 on a side opposite to the shaft-like member 49 for a purpose hereinafter described.

An expansible element 91 is disposed in the compartment 45 of the housing 41 and has the movable wall 92 thereof engaging the end 90 of the lever 88 at a point 93 to tend to pivot the lever 88 about the fulcrum point 89 in a clockwise direction upon expansion of the fluid in the expansible element 91 for a purpose hereinafter described, the expansible element 91 being adjustably mounted to the housing member 44 by means of a threaded portion 94 being threadedly disposed in a threaded bore 95 passing through the housing member 44.

The interior of the expansible element 91 is adapted to be interconnected to a temperature sensing bulb 97 by a conduit means 98 in the manner illustrated in FIG- URE 1 whereby the bulb 97 senses the temperature of the outside heat exchanger 11 for a purpose hereinafter described.

A compression spring 99 is disposed in the compartment 45 of the housing 41 and has one end 100 bearing against the housing member 42 and the other end 101 bearing against the end 90 of the lever 88 on a side opposite to the expansible element 91 for a purpose hereinafter described.

- After the control device 25 is mounted in the system in the manner illustrated in FIGURE 1, such as by mounting the control device 25 in any suitable position by a mounting member 102 projecting from the housing member 27, the control device 25 can be set to automatically control the operation of the outside heat exchanger 11 in a manner hereinafter described.

For example, the adjusting member 87 can be so adjusted relative to the housing member 44 that the shaftlike member 49 will not move from the position illustrated in FIGURE 3 to the position illustrated in FIG- URE 5 until the pressure differential between the inlet and the outlet side of the heat exchanger 11 has reached a predetermined value. Similarly, the adjusting portion 94 of the expansible element 91 can be adjusted relative to the housing member 44 so that the expansible element 91 will not terminate the defrosting operation on the heat exchanger 11 until the heat exchanger 11 has reached a desired temperature as will be apparent hereinafter.

The operation of the control device 25 in the system 10 of this invention will now be described.

,When the system 10 has the selector switch 21 thereof set in a position to cause the :reversing valve 14 to interconnect the outlet 15 of the compressor 13 with the conduit of the heat exchanger 12, it can be seen that the inside heat exchanger 12 acts as a condenser to heat the air circulated around the same for a heating cycle thereof whereby the outside heat exchanger 11 acts as an evaporator. However, during such heating cycle of the system 10, ice and frost begin to bulid up on the outside heat exchanger 11 and thus impede the flow of air from right to left through the heat exchanger 11.

As the ice and frost build up on the heat exchanger 11, it can be seen that the pressure being sensed by the conduit 36 begins to increase over the pressure sensed by the conduit 38 whereby the diaphragm means 33 of the control device tends to move from right to left in FIGURES 3 and 5, such movement of the diaphragm 33 being resisted by the force of the compression spring 81.

However, when the pressure differential acting on the diaphragm means 33 exceeds the force of the compression spring 81, the diaphragm means 33 moves from the position illustrated in FIGURE 3 to the position illustrated in FIGURE 5 whereby the shaft-like member 49 pivots the lever 58 about the fulcrum point 59 so that the end 60 thereof moves in a clockwise directionto permit the plunger 63 of the switch construction 64 to move to the right to the position illustrated in FIGURE 5 so that the contacts 66 and 68 are closed in the manner previously described.

When the contacts 66 and 68 are disposed in the closed position illustrated in FIGURE 5, an electrical signal is sent to the solenoid of the reversing valve 14 to cause reversal of the flow of the refrigerant in the system 10 so that the conduit means 17 of the outside heat exchanger 11 is now interconnected to the outlet side 15 of the compressor 13 whereby the heat exchanger 11 now acts as a condenser and begins to heat up to melt the frost and ice on the same.

When the heat exchanger 11 heats up to a predetermined temperature, as set by the adjustable sensing element 91, the temperature sensing fluid in the bulb 97 expands and causes the movable wall 92 of the expansible element 91 to move to the right in opposition to the force of the compression spring 99 and cause the lever 88 to move in a clockwise direction and assist the action of the compression spring 81 tending to move the shaftlike member 49 back to the right so that the end 60 of the lever 58 can again move in a counterclockwise direction and cause the plunger 63 to move to the position illustrated in FIGURE 3 to open the contacts 66 and 68 in the manner previously described.

Thus, it can be seen that the condition responsive means or expansible element 91 determines when the heat exchanger 11 has been heated to the desired temperature so that melting of the frost and ice can take place and will cause the reversing valve 14 to again interconnect the outlet side 15 of compressor 13 to the conduit 20 of the inside heat exchanger 12 so that the outside heat exchanger 11 will again act as an evaporator whereby the system 10 will again perform its heating cycle.

Thus, it can be seen that the control device 25 of this invention will automatically initiate the defrosting cycle of the heat exchanger 11 when the pressure drop across the coils thereof reaches a predetermined value and will automatically terminate the defrosting operation when the temperature of the coil of the heater exchanger 11 has reached a predetermined value whereby the heat exchanger 11 can be maintained substantially frost-free to prevent a drop in the efficiency of the system 10 when the same is disposed in its heating cycle.

However, when the system 10 is disposed in its cooling cycle by having the selector switch 21 disposed in the proper position so that the reversing valve 14 interconnects the outlet side 15 of the compressor 13 with the outside heat exchanger 11, the temperature of the heat exchanger 11 acting as a condenser is sensed by the sensing bulb 97 so that the movable wall 92 of the expansible element 91 is moved sufficiently far to the right in the drawings so that the lever 60 is maintained in the position illustrated in FIGURE 3 whereby no false defrosting can take place during summer operations, the end 60 of the lever 58 having a suitable stop 103 to abut aginst the housing 65 of the switch construction 64 to prevent overshooting of the lever 58 in a counterclockwise directional movement thereof. i

By providing the diaphragm means 33 of the control device 25 of this invention in a separate housing 26 from the housing 41 containing the lever actuating means of the electrical switch construction, it can be seen that no problem is presented for sealing one side of the diaphragm means 33 as in prior art devices.

Further, the compression spring 81 is so constructed and arranged that adjustment thereof by the adjusting member 85 can take place exteriorly of the control device 25 even after the control device 25 has been mounted in one particular position thereof.

In addition, the control device 25 of this invention is insensitive to vibration and position. Thus, with vibrations present for changes in the effect of gravity on the various parts of the control device 25 due to the mounted position thereof, the various masses involved in the control device 25 would set up forces which would act on the lever system. However, the vibration and position insensitive feature of the control device 25 of this invention has been obtained by making the clockwise forces acting on the switch lever 58 which are so produced equal to the counterclockwise forces acting on the switch lever 58 which are also produced by variation or position.

Further, the control device 25 of this invention is compact and rugged and simple to manufacture whereby the'overall cost of the same is relatively small when compared with prior art control devices of a similar type.

Thus, it can be seen that not only does this invention provide an improved defroster control device or the like, but this invention also provides improved parts for such a defroster control device or the like.

While the form of the invention now preferred has been disclosed as required by the statutes, other forms may be used, all coming within the scope of the claims which follow.

What is claimed is:

1. A defroster control or the like comprising a first housing having a compartment therein divided into two chambers by a movable diaphragm means, a second housing interconnected to said first housing and having a compartment therein, electrical switch means in said compartment of said second housing and having an open position and a closed position, means interconnecting said diaphragm means with said switch means whereby movement ofsaid diaphragm means operates said switch means between its open and closed positions, said diaphragm means causing said switch means to move to one of its positions to cause a defrost cycle when said defrost control detects a defrost condition, and a separate and independent condition responsive means interconnected to said switch means only to move said 'switch means back to the other position thereof to terminate the defrost cycle when said condition responsive means senses that the defrost cycle has been accomplished to a predetermined condition.

2. A defroster control or the like as set forth in claim 1 wherein said interconnecting means includes 'a post-like member interconnected to said diaphragm means and projecting into said compartment of said second housing.

3. A defroster control or the like as set forth in claim 2 wherein said housings have aligned openings respectively receiving said post-l'ike member.

4. A defroster control or the like as set forth in claim 3 wherein an annular member surrounds said openings of said housing and carries a flexible seal interconnected to said. post-like member to seal said compartment of said first housing from said compartment of said second housing.

5. A defroster control or the like as set forth in claim 1 wherein a spring means is disposed in said compartment of said second housing and tends to move said diaphragm means in one direction.

6. A defroster control or the like as set forth in claim 5 wherein said second housing carries adjusting means for adjusting the force of said spring means tending to move said diaphragm means in said one direction,

7. A defroster control or the like comprising a housing means, a first condition responsive means'carried by said housing means and movable relative thereto, electrical switch means carried by said housing means and having opened and closed positions, a. first lever pivotally mounted to said housing means at a point intermediate the ends of said first lever, one end of said first lever being engageable with said switch means and the other end of said first lever being engageable with said first condition responsive means, a second lever pivotally mounted to said housing and having one end thereof engageable with said other end of said first lever on a side thereof opposite to said first condition responsive means, and a second condition responsive means carried by 'said housing means and engaging said second lever to tend to pivot said second lever in a direction to cause said first lever to move said switch means to it's open position upon movement of said second condition responsive means in one direction, said first condition responsive means causing said switch means to move to one of "its positions to cause a defrost cycle when said defrost control detects a defrost condition, and said second condition responsive means causing said switch means to move back, to the other position thereof to terminate said defrost cycle when said second condition responsive means senses that the defrost cycle has been accomplished to a predetermined condition.

8. A defroster control or the like as set forth in claim 7 wherein said second condition responsive means is adjustably mounted to said housing means.

, 9. A defroster control or the like 'as set. forth in claim 7 wherein spring means is carried by said housing means and tends to pivot said second lever in a direction opposite to said movement of said second condition responsive means in said one direction.

10. A defroster control as set forth in claim 7 wherein said second condition responsive means comprises an expansible element.

References Cited by the Examiner UNITED STATES PATENTS 2,427,426 9/1947 Swenson et al 20014O 2,751,457 6/1956 Donaldson 20083 X 2,849,577 8/1958 Pfeiffer 20083 X 2,890,305 6/1959 Gutowski 20083 2,971,070 2/1961 Snoberger ZOO-@815 X 3,005,887 10/1961 -Robs0n 200 -83 X 3,182,149 5/1965 Noakes 20083 X 3,194,915 7/1965 Anderson 2OO83 BERNARD A. GILHEANY, Primary Examiner.

M. FLECK, G. J. MAIER, Assistant Examiners. 

1. A DEFROSTER CONTROL OR THE LIKE COMPRISING A FIRST HOUSING HAVING A COMPARTMENT THEREIN DIVIDED INTO TWO CHAMBERS BY A MOVABLE DIAPHRAGM MEANS, A SECOND HOUSING INTERCONNECTED TO SAID FIRST HOUSING AND HAVING A COMPARTMENT THEREIN, ELECTRICAL SWITCH MEANS IN SAID COMPARTMENT OF SAID SECOND HOUSING AND HAVING AN OPEN POSITION AND A CLOSED POSITION, MEANS INTERCONNECTING SAID DIAPHRAGM MEANS WITH SAID SWITCH MEANS WHEREBY MOVEMENT OF SAID DIAPHRAGM MEANS OPERATES SAID SWITCH MEANS BETWEEN ITS OPEN AND CLOSED POSITIONS, SAID DIAPHRAGM MEANS CAUSING SAID SWITCH MEANS TO MOVE TO ONE OF ITS POSITIONS TO CAUSE A DEFROST CYCLE WHEN SAID DEFROST CONTROL DETECTS A DEFROST CONDITION, AND A SEPARATE AND INDEPENDENT CONDITION RESPONSIVE MEANS INTERCONNECTED TO SAID SWITCH MEANS ONLY TO MOVE SAID SWITCH MEANS BACK TO THE OTHER POSITION THEREOF TO TERMINATE THE DEFROST CYCLE WHEN SAID CONDITION RESPONSIVE MEANS SENSES THAT THE DEFROST CYCLE HAS BEEN ACCOMPLISHED TO A PREDETERMINED CONDITION. 